Chromosomal instability by low-coverage whole-genome sequencing assay predicts prognosis in bladder cancer patients underwent radical cystectomy.

Purpose: To investigate chromosomal instability (CIN) in tumor tissue from radical bladder resection and to evaluate whether it can be used as a biomarker for the molecular typing of (BC).

Methods: DNA was extracted from formalin-fixed paraffin-embedded samples of 50 BC patients who were followed up to March 23 2023 using the Qiagen nucleic acid kits. We analyzed CIN in tumor of bladder by low-coverage whole genome sequencing (LC-WGS). Kaplan-Meier log-rank test was used to perform survival analysis. The association between variables and overall and progression-free survival was analyzed using the Cox proportional hazards model.

Results: There were 44 genome segments with statistically significant changes in copy number. CIN was significantly correlated with tumor stage, lymph node metastasis, relapse and survival status. Patients with high CIN were found to have a worse survival, with a median overall survival (OS) of 15 months. In addition, patients with high CIN were more likely to relapse, with a median progression-free survival (PFS) of 7 months. Patients with low CIN showed better OS and PFS. However, there was no significant difference in OS and PFS between T2 and T3-T4 patients. Multivariate cox regression analysis showed that high CIN was an independent predictor of OS, and high CIN and muscle invasion were independent predictors of PFS. Furthermore, patients with abnormal copy number of a single chromosome also had a poor prognosis, with a median survival of 14-30 months for OS and 5-10 months for PFS, while negative patients had a better prognosis.

Conclusion: CIN was significantly correlated with tumor stage, lymph node metastasis, relapse and survival status of BC. Patients with high CIN or abnormal copy numbers of a single chromosome have a poor prognosis. CIN might be better than T stage in predicting the prognosis of patients with BC. Molecular typing of CIN can be used as an independent prognostic factor for BC.